An interface card, such as a PCIe (Peripheral Component Interconnect Express) card, is disposed on a mount bracket of a computer case of a desktop computer. During the operation of the computer, electronic components in the computer may generate electromagnetic interference (EMI) which may generate an adverse effect on the interface card. To prevent this problem, a conductive sheet is disposed on the mount bracket for contacting the interface card and the mount bracket at the same time. Accordingly, the interface card can be electrically connected to the mount bracket via the sheet, and the interface card can be grounded by the sheet and thus reducing the electromagnetic interference on the interface card.